This invention relates to hand tools for manipulating electrical connectors and, more particularly, to a wrench for turning a mechanical grip for a jumper clamp.
Background: Electrical Distribution Line Construction Maintenance and Repair
Commonly, an electrical distribution system uses three-phase alternating current (AC) electricity to transmit electrical energy from a generating source to a consumer. Each phase is transmitted over a separate distribution line. Each distribution line is electrically isolated from the other two in order to avoid a short circuit, which would create a potentially hazardous over-current condition.
During the construction, maintenance or repair of electrical distribution lines, it is often desirable and necessary to provide uninterrupted electrical service to a utility""s customers. In order to provide uninterrupted service, a method of re-routing electricity around breaks in distribution lines must be used.
A common method of re-routing practiced by linemen in utility maintenance crews is to use a series of jumper wires to reroute the electricity. Either the lineman will climb a utility pole to get to the distribution lines or a bucket truck will lift the lineman up to the distribution lines. The utility lineman will attach one end of the jumper wire to a distribution line, upstream of a switch. The lineman then connects the other end of the jumper wire to another section of distribution line such that the jumper wire, in conjunction with the downstream switch, will electrically bypass the region of distribution line on which the lineman wishes to work. By using a separate jumper wire for each phase, the lineman can re-route all three phases so that uninterrupted electrical service is provided to the utility""s consumers even while the lineman make repairs of strings new distribution lines.
Background: Jumper Wire Mechanicals
Linemen use specialized jumper wires for electrical distribution lines. As shown in FIG. 1A, the jumper wires 50 typically consist of heavy gauge wire 60 with one heavy-duty connector 100 at each end. Linemen commonly refer to these connectors 100 as xe2x80x9cmechanicals.xe2x80x9d A typical mechanical 100 is shown in FIGS. 1B and 1Bxe2x80x2. The jumper wire 60 is usually encased in an electrically nonconductive rubber or plastic material, for example, but portions of the mechanical 100 are bare metal.
Mechanicals 100 for the jumper wire 60 are designed to be tightened by hand, and indeed, that is how linemen presently attach them to distribution lines. As shown in FIG. 1B, the typical mechanical 100 has two main components, a metal hook 110 and a grip 120 made of an electrically non-conductive material, for example, plastic. A tail portion 115 of the hook 110 extends into the grip 120 and is connected to the jumper wire 60. The tail portion 115 is threaded. The inner surface of the grip 120 is threaded so that the grip 120 will travel along the threads of the tail 115 as grip 120 is turned. Metal washer 130 moves in relation to hook 110 as grip 120 is turned. As the metal washer 130 moves towards the hook 110, electric distribution line 150 is compressed between washer 130 and hook 110. Grip 120 has a plurality (usually two diametrically opposed) of raised ridges 140 disposed on its periphery that run the length of the grip. Ridges 140 allow the lineman to grasp the mechanical 100 securely and get leverage to turn the grip 120. Typically, the grip 120 is threaded on its inner surface so that it will easily travel along the threads of the tail 115. The hook 110 has matching threads so that the grip 120 will move either closer to, or further from, the hook 110 as the grip is rotated. Although the lineman wears rubber gloves, flange 155 reduces the possibility of contact between the lineman""s hand and the metal hook 110, distribution line 150, or washer 130. Ideally, the lineman causes the hook 110 to firmly hold a distribution line by rotating the grip such that the distribution line 150 is compressed between hook 110 and washer 130.
FIGS. 1C and 1Cxe2x80x2 show a common variation of the jumper mechanical. In this variation, a plurality of protrusions 160 allow the lineman to graph and rotate the grip. The protrusions 160 are typically block-shaped and arranged longitudinally in parallel rows.
Background: Effects of Loose Electrical Connection
No matter how tightly a lineman may tighten a jumper mechanical by hand, it will often loosen due to forces beyond the lineman""s control such as wind shaking the distribution lines, or contraction and expansion of the mechanical due to variations in weather. The effects of a loose connection to a distribution line can be catastrophic. Because electrical distribution lines carry high voltages, loose connections to distribution lines can cause dangerous electrical arcing which may bum the lineman or cause interruption of electrical service. High temperatures due to the increased electrical resistance across the loose connection can result in hazardous fires that may end in loss of property or life. Mechanicals and jumpers often are melted completely through by the extreme heat caused by a loose connection. The dangling remnants of the jumper often touch other distribution lines causing a direct short circuit between different phases and a sudden power outage due to the current rush through the short circuit. If the jumper touches television cables or telephone lines, it may also cause damage to many televisions and phones and harm persons using them.
Background: Wrenches
A wrench is a type of tool commonly used to hold or apply rotational force to nuts, bolts, and pipes. Familiar types of wrenches are the open-ended wrench, the monkey wrench, and the Stillson (pipe) wrench. Hundreds of different wrenches have been awarded United States patents, most of them for tools which are adapted to hold or rotate with work pieces with circular or polygonal cross sections.
For example, U.S. Pat. No. 463,137, awarded to Carpenter, discloses an open-end wrench having a jaw with a plurality of transverse notches. The edges of the transverse notches will engage adjacent linear faces of a polygonal nut. The notches allow the wrench to be rotated to obtain a fresh hold on the nut without removing the wrench from the nut.
For example, U.S. Pat. No. 1,624,508, awarded to Reilly, discloses an open-end, fixed jaw wrench which can hold nuts and bolts of various sizes. The wrench of Reilly has one jaw with a smooth face and an opposite jaw with a stepped face. The steps are sized so that the jaws will engage the flat faces of various sizes of polygonal nuts.
For example, U.S. Pat. No. 2,334,069, awarded to Collins, et al., discloses an open end wrench designed to turn coupling nuts for joining hoses such as fire hoses or oil hoses. This wrench is intended to be used with three general types of coupling nut, all of which have diametrically opposed pegs (lugs). The head of the wrench has a cavity that fits over one peg on the coupling nut. In addition to engaging one peg, the wrench has a working face that engages the perimeter of the coupling nut somewhere between the two pegs.
Prior inventions appear to have focused almost exclusively on wrenches which can hold or rotate nuts, bolts, or pipes. There has been a conspicuous lack of wrenches created to accommodate work pieces which have protruding features. In particular, there has not been an adequate wrench designed to manipulate jumper mechanicals.
One or more of the disclosed embodiments provides at least the following advantage: a tool for improved manipulation of jumper mechanicals.
One or more of the disclosed embodiments provides at least the following advantage: a tool that will work with many different jumper mechanical grips.
One or more of the disclosed embodiments provides at least the following advantage: a tool that may be used easily and safely in the confines of a bucket truck.
One or more of the disclosed embodiments provides at least the following advantage: a tool that can apply rotational force to two diametrically opposed features, such as longitudinal ridges, on a mechanical grip.
One or more of the disclosed embodiments provides at least the following advantage: a tool that can spread rotational force along a substantial portion of a longitudinal feature that runs parallel to the axis of rotation, such as a ridge, on a mechanical grip.
In the presently preferred embodiment of the invention, a tool has a cut-out which will engage the grip of a jumper mechanical. The cut-out has a notch that fits over a first ridge on the mechanical grip. A plate engages the first ridge so that rotating the handle of the tool about the longitudinal axis of the mechanical""s grip will cause the grip to travel along the threads of the tail portion of the hooks. The plate spreads the rotational force along the length of the ridge, parallel to the axis of rotation, rather than concentrating it in one area. The plate may be a semicircle, rectangle, or any suitable shape. The increased force provided by the tightening tool creates a more secure jumper connection which may be less susceptible to failure and arcing.
If the grip has a second ridge, a knob on the handle may engage the second ridge such that the knob may push against the second ridge as the handle of the tool is rotated about the longitudinal axis of the mechanical""s grip, providing increased leverage for tightening the mechanical.